ISSN 1424-8220 www.mdpi.org/sensors Article
Sensing and 3D Mapping of Soil Compaction
Yücel Tekin 1,*, Basri Kul 1 and Rasim Okursoy 2 1 Uludağ University, Vocational School of Technical Sciences, 16059 Görükle Campus, Bursa – Turkey; E-mail: email@example.com 2 Uludağ University, Faculty of Agriculture, Department of Agricultural Machinery, 16059 Görükle Campus, Bursa – Turkey; E-mail: firstname.lastname@example.org * Author to whom correspondence should be addressed; E-mail: email@example.com; Tel.: +90-224-294-2354; Fax: +90-224-294-2303 Received: 18 March 2008 / Accepted: 21 May 2008 / Published: 26 May 2008
Abstract: Soil compaction is an important physical limiting factor for the root growth and plant emergence and is one of the major causes for reduced crop yield worldwide. The objective of this study was to generate 2D/3D soil compaction maps for different depth layers of the soil. To do so, a soil penetrometer was designed, which was mounted on the three-point hitch of an agricultural tractor, consisting of a mechanical system, data acquisition system (DAS), and 2D/3D imaging and analysis software. The system was successfully tested in field conditions, measuring soil penetration resistances as a function of depth from 0 to 40 cm at 1 cm intervals. The software allows user to either tabulate the measured quantities or generate maps as soon as data collection has been terminated. The system may also incorporate GPS data to create geo-referenced soil maps. The software enables the user to graph penetration resistances at a specified coordinate. Alternately, soil compaction maps could be generated using data collected from multiple coordinates. The data could be automatically stratified to determine soil compaction distribution at different layers of 5, 10,.…, 40 cm depths. It was concluded that the system tested in this study could be used to assess the soil compaction at topsoil and the randomly distributed hardpan formations just below the common tillage depths, enabling visualization of spatial variability through the imaging software. Keywords: Soil compaction, Soil mapping, Penetration resistance, GPS
Sensors 2008, 8 1. Introduction
Soil examination techniques in the field have been widely used for many centuries. They are used for evaluating the quality of land, for studies of soil genesis, soil compaction, erosion control, and for tillage management . Soil compaction is an important physical limiting factor for the root growth and plant emergence, decreasing crop production worldwide. It is often caused by heavy axle loads of agricultural machines such as tractors and self-propelled harvesters as well as other equipment used in agro-technical operations during planting and vegetation. Soil compaction may significantly debilitate the production capacity of soil by reducing porosity, creating obstacles to air, water, nutrient movements and root penetration [2, 3]. In addition, soil compaction reduces rate of leaf appearance and ground cover expansion, shortened canopy cover duration and restricted light interception, which combined to reduce tuber yield . Reductions in grain yield attributable to soil compaction for several climate and crops in a wide range of soils from sands to heavy clays [5-9]. Moreover, the subsoil becomes a compacted soil layer which prevents water from infiltrating into deeper layers, resulting in reduced porosity at topsoil and decreased yields . Therefore, researchers are interested in focusing on subsoil compaction and the methods of tillage to control the compacted layer [11, 12]. Although some researchers show no statistical conclusion could be drawn on the effect of subsoiling on crop yields , the soil compaction should be mapping to reduce draft force. Site-specific subsoiling resulted in 59% and 35% reduced draft force in the shallow depth hardpan plots (25 cm) and medium...